Ruth Wyner, 50, a highly respected and experienced professional, who ran the Wintercomfort day centre for the homeless in Cambridge, has so far spent five months of a five-year sentence behind bars because a court found her and her co-worker John Brock guilty of "knowingly" allowing drugs to be dealt on the premises.

The sentence was longer than that handed out to the dealers and has sent shockwaves through the voluntary sector.

People running youth clubs, homeless hostels, drug projects and even schools could all now face imprisonment unless they introduce draconian and invasive measures, such as CCTV cameras and sniffer dogs to ensure no drugs are dealt on their premises.

And the Comet can reveal that Kingston's nationally famous drug project, Kaleidoscope, has already been investigated as a result of the ruling. But the director has pledged not to change its open-door policy.

However, other hostels and homeless projects have already reluctantly altered their open-door policies which may prevent people getting the help they so desperately need.

On Wednesday - the anniversary of Ms Wyner's fifth month in jail - the High Court granted her leave to appeal against her conviction on July 11.

Michael Mansfield QC, who represented Steven Lawrence's family, has agreed to present the case without fee.

Ms Wyner was jailed for five years in December under section 8 of the 1971 Misuse of Drugs Act, following a five-month undercover police operation.

Section 8 of the act was originally introduced to catch the owners of pubs and clubs who profited from drug dealing on their premises. The Wintercomfort case set a precedent, as it was the first time the law was used against the managers of charitable premises.

Throughout the seven week trial Ms Wyner insisted that they had done everything reasonable to prevent drug dealing, but the court decided they should have done more.

The Reverend Martin Blakebrough who heads Kaleidoscope said: "The law as it now stands is that people should do everything reasonable to prevent drug dealing.

"The question is what is reasonable. It is not reasonable to have sniffer dogs outside the project.

"This law is creating a system of apartheid. There is a danger that this will set a precedent where we can not serve the marginalised people of the community.

"This is already what is happening with hostels refusing a bed to people with a drug history.

The implications of the case spread beyond the work of the charity sector. Teachers, youth workers and prison officers could be held liable, even if they are unaware there are drugs on their premises."

Today the Comet is urging readers to back the campaign to release Ruth Wyner and her colleague at once, and for the law surrounding the case to be clarified to ensure that those helping people on the margins of society can continue their vital work without fear of imprisonment.

The campaign has the backing of both Kingston and Richmond Park MPs.

Speaking from Highpoint Prison last week, Ms Wyner said: "I've worked for 20 years with the homeless and the dispossessed, trying to put together shattered lives.

"I think it is fantastic that the Surrey Comet is taking the case up and I am very grateful. I am sure that pressure from the public does make a significant difference in these cases."

q For more on the case and full details on how to back the campaign see page four.